Which of these electronic transitions in hydrogen is exothermic? question 11 options:

a. from n=3 to n=2

b. from n=1 to n=3?

The answer is Option a Reason The electron is moving closer to the nucleus. That is, in other words, it is moving to a lower energy level and will, therefore, give out energy When a transition gives out energy or in other terms it emits heat, it's exothermic. Hence the option a.